Rotary type compressors have been known in the past in which the discharge valve, for opening and closing a discharge passage in fluid communication with a compression chamber, is formed using a reed valve. This type of discharge valve is made up of a valve disc of plate shape and a valve guard for restricting the amount of deformation of the valve disc, and is set on the back surface side of an end plate part whose front surface faces the compression chamber. The valve disc is disposed along the back surface of the end plate part. The valve guard is disposed on the back surface side of the valve disc.
In a rotary type compressor which employs a discharge valve of the aforesaid type, the discharge passage becomes a dead volume (that is, the fluid which has not been discharged stays therein in the process of compression). To cope with this, it is preferred that the length of the discharge passage be as short as possible. However, if in order to reduce the length of the discharge passage, the peripheral thickness of the discharge passage of the end plate part is reduced to form a receding part, this weakens the strength of the end plate part at the receding part. In this case, at the time when the compression chamber is in the low pressure state, the receding part deforms towards the compression chamber due to the difference in pressure between the compression chamber side and the discharge space side, thereby resulting in leakage of refrigerant from the compression chamber. This causes a problem that there is a drop in efficiency of the compressor. In addition, since the valve disc and the valve guard are firmly attached to the receding part of thin thickness by use of a bolt, this causes another problem that the receding part becomes distorted when tightening up the bolt.
JP-A-1987-243984 therefore discloses a rotary compressor with a discharge valve for providing solutions to the above-described drawbacks. Referring to FIG. 14, there is shown a cross sectional view of the discharge valve of the aforesaid patent document. In this rotary compressor, the receding part is formed on the back surface side of a bearing which is an end plate part whose front surface faces the compression chamber, and a discharge hole is opened at the bottom surface of the receding part. In the receding part, the wall surface on the side where a valve disc and a valve guard are mounted is an inclined surface. A bolt, used to firmly attach the valve disc and the valve guard to the inclined wall surface, is provided above a relatively thick portion of the inclined wall surface of the receding part.